Cling signage

ABSTRACT

A multilayered cling signage sheet for use in conventional printers, including laser printers. The sheet includes a first layer to provide structural integrity to the sheet. A second print receptive layer is adhered to one side of the first layer. A third layer which is a low modulus cling elastomer is adhered to the other side of the first layer. The cling elastomer is characterized in that it will releasably adhere to a substantially flat surface.

This is a divisional of application Ser. No. 08/349,628 filed on Dec. 5,1994 now U.S. Pat. No. 5,601,927.

FIELD OF THE INVENTION

The invention relates to cling signage, specifically, a flexible sheetwhich can be used in conventional computer printers, copy machines andany other industrial printing technique for printing on the sheet andwhich sheet, when in use, repeatedly releasably engages a flat surface.

BACKGROUND OF THE INVENTION

Standard cling signage comprises releasable flexible plastic filmshaving visual indicia printed on one side thereof. The plastic film istypically a highly plasticized polyvinyl chloride approximately 0.016"thick. This film requires the use of a heavy gauge release paper tosupport it during the printing process. When the film is placed againsta flat surface, usually glass, it clings to the surface. The film iseasily released from the surface and can be re-adhered to a surfaceseveral times. The present drawbacks with cling signage are that it isdifficult to print on the highly plasticized PVC film, the cost isrelatively high, it is relatively bulky, and it is difficult to apply atcold temperatures. Perhaps the most significant drawbacks are the costand difficulty of printing on the highly plasticized surface.Furthermore, the films cannot be used in existing printing machinesand/or copy machines.

The present invention embodies a laminated sheet for cling signage. Thesheet overcomes all of the limitations of cling PVC signage andparticularly, the sheet of the invention is processable on all copymachines, computer printers, pen plotters, offset and litho presses andscreen printers. The sheet of the invention is relatively thin, 0.00048"to 0.00100", compared to prior art cling signage, 0.016". This thinnessallows the sheet to be used in all types of computer printers and copymachines.

The sheet as a minimum comprises a support film, i.e. a polyester film,a print receptive coating on one side of the film and an adhesivecoating on the other side of the film. The print receptive coating isselected based on its ability to adhere to the film and itsreceptiveness to have an image formed thereon. That is, depending uponwhether the sheet of the invention is to be used with a laser printer,color ink jet printer, lithopress, etc., the print coating will beselected based on the intended printing process.

The adhesive coating is referred to herein as a cling. elastomericcoating. As will be described, it distinguishes from those coatingscommonly referred to as pressure sensitive adhesive coatings in that itdoes not loose its effective adhesive characteristics over a series ofrepeated applications as do most pressure sensitive adhesive coatings.

Broadly, the sheet comprises a plurality of layers including a top layerwhich is a print receptive coating. The print receptive top layer can becustomized to work with all types of commercially available ink andimaging systems.

The print receptive coating will vary in composition depending on theprint market in which it will be used. Styrene/acrylic polymers withsilica fillers are known to work in thermal transfer printing. Polyesteror acrylic polymers with silica fillers are known to work in copymachines, laser printers, dot matrix, offset, litho and screen printingapplications. Polyvinyl pyrrolindones and ethyl celluloses are known towork in ink jet applications. Print receptive coatings have beendeveloped for polyethylene terphalate and other orientated films thatwork in all the different types of printing equipment. Although attemptshave been made, as a practical matter, nothing can be done to make thepolyvinyl chloride cling signage processable on copy machines andcomputer printers.

The next adjacent layer is an oriented film to provide structuralintegrity to the sheet when used as signage. This layer is an orientedfilm that will vary in thickness and type dependent on the applicationand market. Both clear and opaque white polyethylene terphalate andbiaxially oriented polypropylene in thicknesses ranging from 0.00048" to0.00100" can be used depending on the end use market.

The next adjacent layer is a coating of a cling elastomer. The clingelastomer used in the preferred embodiment of the invention has a Tg of-65° C. which allows a functional temperature range of -65° C. to 160°C. compared to the 0° C. to 80° C. range of the prior artpolyvinylchloride. The cling elastomer used is not a pressure sensitiveadhesive and can be cleaned and reused indefinitely. Pressure sensitiveadhesives, once contaminated, no longer adhere.

The cling elastomeric coating will vary in thickness and polymer typedependent on application and end market. The elastomers of choice areeither silicone or polyurethane based. Platinum catalyzed addition curedsilicone polymers are preferred because of their processing advantages.Diphenylmethane diisocyanate or toluene diisocyanate cured urethanes arealso preferred because of their low modulus and processing advantages.

The next layer is a film to protect the elastomer and to providedimensional stability to the sheet. The layer preferably is an orientedfilm or polycoated paper that will vary in thickness and type dependenton the market. This layer's function will be to protect the elastomerfrom contamination and to provide physical support to the constructionduring the printing process.

The next and last layer is a friction coating such as polyester filledwith silica to facilitate the use of the sheet in conventional printingand copying machines.

The print receptive layer, elastomers and friction layer are applied inroll to roll processes that include but are not limited to the followingtypes of coating methods: meyer rod, gravure, offset gravure, reverseroll, knife over roll and slot die. The proper combinations of the layerthicknesses can be used to allow processability on all copy machines andcomputer printers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a sheet embodying the invention;and

FIG. 2 is a flow diagram of a process embodying the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The following illustrative example of an embodiment of the invention issolely for purposes of illustration and not limitation.

Referring to FIG. 1, a sheet 8 embodying the invention comprises a firstlayer 10 which is a print coating; a second layer 12 which is a flexiblefilm such as a biaxially oriented polyester film; a third layer 14 whichis a cling elastomeric coating; a layer 16 which is a protective filmand a layer 18 which is a coating to impart a frictional surface to thefilm 16 to facilitate the use of the sheet in a printing process.

The example of the invention will be described in reference to thepreparation of cling signage which is suitable for use in the standardstate-of-the-art laser printers.

Referring to FIG. 2, the film 12 of PET having a thickness of between0.00092" to 0.00495" passes between rollers 20a and 20b where a knife 22applies a print coating 10, having a print receptive surface, to theroller 20a. The coating is then transferred to the film 12. Specificallythe coating is polymethacrylate filled with silica in an amount of 20%by weight based on the total weight of the coating and is applied in athickness of between 0.00010" to 0.0010". The coating is dried and curedby passing under a heater 24 at a temperature between 190° to 260° F.

The film 12 with the print coating 10 has its orientation reversed andpasses through rollers 26a and 26b where the cling elastomeric coating14, e.g. silicone, specifically a platinum catalyzed addition curedsilicone is cast on the roll 26a by a knife 28 in a thickness of between0.0002" to 0.0020". This coating is transferred to the film 12. Thecoating is then dried and cured by passing it under a heater 30 at atemperature of between 180° to 300° F.

The protective film 16, e.g. PET, in a thickness of between 0.00092" to0.00492" contacts the coating 14 which then passes through nip rollers32a and 32b at a nip pressure of 2#/in to adhere the film 16 to thecoating 14.

This laminate 10, 12, 14 and 16 then passes through rollers 34a and 34bwhere a knife 36 applies the friction coating 18, e.g. a silica filledpolyester, specifically a 30% by weight loading of silica, in athickness of 0.0002" to 0.0020" to the roller 34a to form the sheet 8.The coating 18 passes under a heater 38 and dried at a temperaturebetween 160° to 250° F.

The fully formed sheet is then either rolled and stored for further useor cut to size and packaged.

For this example, typically the sheet 8 would be cut to 81/2" by 11"size for use in a laser printer. In a laser printer the sheets to beused for printing are simply stacked and placed in the printer tray aswith ordinary bond paper. Depending upon the visual indicia desired, itis simply printed on the surface 10 via the computer instruction.

When ready for use as cling signage, the protective film 16 togetherwith the associated coating 18 are peeled from the coating 14 and thecoated surface 14 adheres to a flat surface, particularly a flat glasssurface.

The foregoing description has been limited to a specific embodiment ofthe invention. It will be apparent, however, that variations andmodifications can be made to the invention, with the attainment of someor all of the advantages of the invention. Therefore, it is the objectof the appended claims to cover all such variations and modifications ascome within the true spirit and scope of the invention.

Having described my invention, what I now claim is:
 1. A method for theformation of cling signage comprising:coating one side of a first layerof film having structural integrity with a second layer of a printreceptive coating; coating the other side of the first layer with athird low modulus cling elastomeric layer having a thickness of betweenabout 0.0002 in to 0.0020 in, the cling elastomer characterized in thatit will releasably and repeatably adhere to a substantially flatsurface.
 2. The method of claim 1 which comprises:adhering a fourthprotective layer to the third cling elastomer layer.
 3. The method ofclaim 2 which comprises:coating a fifth friction enhancing layer ontothe fourth layer.